Payen BK450 — the original composite reinforced head gasket fitted by Rover on all large-bore engines, including Metro and MG Turbo models. This asbestos-free design features copper-type sealing rings and provides a compressed volume of approximately 3.3cc. Although this gasket has since been superseded by GUG702560HG—which incorporates a black rubber-style O-ring on the rocker feed gallery—many customers still prefer the original TAM1521 Payen version without the rubber seal. Its long-proven reliability, especially in competition applications, continues to make it a popular choice.
Thoroughly clean both the cylinder head and block surfaces. Verify flatness using a straightedge and feeler gauges.
Install the head studs into the block by hand, tighten lightly, and apply oil to the threads.
Fit the new gasket dry, placing it over the studs onto the block.
Install the cylinder head and rocker shaft, ensuring nothing is fouling or obstructed.
Torque the head nuts in the correct sequence, increasing in roughly 5 ft-lb increments up to 45 ft-lb total. Recheck all nuts to confirm consistent final torque. Follow Rover instructions regarding washers, which are required only on the front studs.
Set valve clearances.
Start the engine without coolant and let it run for 2–3 minutes.
Allow the engine to cool for approximately one hour.
Fill with coolant, then restart the engine.